Regulation of soil microorganisms and phosphorus cycling genes on soil phosphorus availability in desert steppe under warming and phosphorus input

Climate warming can directly or indirectly influence soil phosphorus (P) availability. Soil microorganisms are essential driving forces of P cycling. However, how the soil microbes and P cycling genes respond to variations in soil P availability on climate warming in the P-limited desert steppe is unclear. In this study, we conducted a field experiment using two temperature levels (control, warming) and three P fertilizer addition rates (0, 5, 10 g P m⁻²·yr⁻¹) in the desert steppe. Microbiological and metagenomic analyses were used to explore the shifts in the relative abundance and compositions of soil microbial and P cycling genes in response to warming and P inputs. The results demonstrated that warming decreased soil labile P (7.04 %) by reducing the percentages of resin-P, NaHCO₃-Pi, and HCl-Pi in inorganic P (Pi). P inputs significantly increased soil TP, MBP, Pi, and inorganic P fractions contents, and further enhanced soil labile P (1.27–3.55 times), moderately labile P (7.04–17.59 %), and stable P (4.23-10.47 %). The interaction of warming and P addition increased NaHCO₃-Pi, the percentages of NaHCO₃-Pi in Pi, and improved soil labile P (1.68–2.05 times) and stable P (5.38–10.38 %). Soil P availability was mainly regulated by TP and MBP, which were positively correlated with the organic P mineralization gene (phnW). Our findings indicated that soil bacteria and fungi did not alter in response to changes in P availability under warming and P input. The phnW gene played an essential role in regulating soil P availability in the desert steppe.